Electrode arrays, having a plurality of electrode probes or shanks, are widely used in biological applications, for example, to stimulate and/or record electrical activity in cells or tissues. By way of illustration, when the cells in nervous tissue (i.e., neurons and neuroglia) or muscle tissue (i.e., muscle cells) are excited, a current is generated. This current results in a change in voltage both inside and outside of the cells. Thus, an electrode array can be used to monitor the changes in voltage and/or to provide a voltage stimulus for the purposes of research, diagnosis, treatment or therapy, and the like.
Many electrode array devices suffer from poor biocompatibility. As part of the body's immunological response to a recognized foreign body, implanted electrode array devices can experience a biofouling process in which local cells surround the probes of the electrode array device and ultimately wall off the implanted device from the body. For example, within hours of implantation of an electrode array device for neural studies, an increased population of astrocytes and glial cells can surround the individual probes of the array. These microglia can then initiate inflammation, and the process of phagocytosis of the foreign material begins. Over time, the astrocytes and microglia begin to accumulate, forming a sheath surrounding the probes of the electrode array that extends tens of micrometers around the device.
As a result of such inflammation and biofouling processes, electrode array devices often must be removed and the same (or another) array must be implanted in another location. This cycle of chronic implantation and removal can result in inflammation, cell loss, scar tissue formation, and the like. Continuing the example of the electrode array device for neural studies described above, chronic implantation and removal of such devices has been shown to lead to neuron loss, axon length reduction, neurodegeneration, and glial scarring.
Accordingly, there remains a need for improved electrode array devices for biological applications. It would be particularly advantageous if the improved devices reduced or eliminated adverse immunological reactions thereto. Such improved electrode array devices would be more effective and have longer service lifetimes.
It is to the provision of such electrode array devices that some of the various embodiments of the present invention are directed.